Influence of pH on the Reactive Brilliant Red X-3B Wastewater Treatment by an Al-Cu Bimetallic System

Abstract

This research investigated the effect of Al-Cu bimetallic system to treat reactive brilliant red X-3B wastewater in different pH value. Meanwhile, the relationship between variation of pH and existing form of dissolved aluminum in reaction system and its influence on the reaction system were studied. In addition, the aluminum surfaces morphologies and matters after long term operation were analyzed by scanning electron microscopy (SEM) in conjunction with energy-dispersion spectroscopy (EDS). The results showed that good treatment efficiency was achieved for batch experiments in experimental conditions of pH 1.5~12.0, particularly noticeable under strong acidic and alkaline conditions (pH=1.5, 12.0). In near neutral pH media, the treatment efficiency almost remained stable after weeks of operation, however, in alkaline media, it gradually decreased with time going but could be recovered by cleaning metal fillings with dilute sulfuric acid solution. Moreover, the results indicated there were three main reasons for the treatment efficiency decreasing over time under alkaline condition. One was the Al(OH) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> precipitates accumulation on the metal surfaces. The other was the adsorption of reactive brilliant red X-3B and reduction products on the metal surfaces. The final and also most important was the induced deposition and adhesion of AlO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> as an enhancing coagulant.